Westinghouse Electric Corporation

Gregg D Auld

David E Murray

Richard D Franklin

Albert R Vaia

Thomas E Dunn

John J Lescisin

Allen J Baum

William J Stenger

Judith B Esposito

An improved method for removing sludge and corrosion products from the interior of a heat exchanger vessel, such as a nuclear steam generator, which comprises the steps of generating a series of pressure pulses within a liquid chelate-containing chemical cleaning agent after the agent has been introduced into the interior of the vessel to create shock waves in the liquid for dislodging, dissolving and fluidizing sludge and corrosion products. The liquid chemical cleaning agent is removed from the vessel after only about 10 to 70 percent of what would have been its normal residence time without the pressure pulses. The method further includes the steps of simultaneously recirculating the chemical cleaning agent through a filter assembly during the pressure pulsing operation in order to remove fluidized sludge and corrosion products dislodged by the pressure pulsing, thereby affording them no opportunity to resettle back onto the surfaces of the heat exchanger vessel and interfere with the chemical cleaning of the vessel. The method reduces not only the time required for a particular chemical cleaning agent to effectively clean the vessel, but further reduces the number of times such chemicals need to be introduced into the vessel, which in turn results in the production of less radioactive liquid waste products.

Chemical cleaning method for steam generators utilizing pressure pulsing

An apparatus for loosening and removing sludge and other impurities from the interior of a heat exchanger vessel which may be the secondary side of a nuclear steam generator is disclosed herein. The apparatus generally comprises a nozzle having a first end that is detachably mountable into an access opening such as a sludge lance port in the secondary side of the generator, and a second end that extends into the interior of the secondary side at a 30 degree downward angle relative to the tubesheet in the vessel for minimizing the stresses applied to the heat exchanger tubes, and for uniformly reflecting the pulse back up toward the upper portions of the secondary side. A pulse generator is operably connected to the nozzle which has a controller for controlling the power level of the pulses generated. To further minimize such peak tube stresses, the pulse generator includes a pulse flattener, and the second end of the nozzle is aligned down the main tube lane.

Pressure pulse cleaning apparatus

Both a system and a method for removing sludge and debris from the interior of the secondary side of a nuclear steam generator is disclosed. The method comprises the steps of introducing a sufficient amount of water in the secondary side to submerge at least the tubesheet, generating a succession of shock waves in the water by means of pulses of pressurized gas to create shock waves that loosen the sludge and debris, and vertically flushing the interior of the secondary side by suctioning water off from the bottom portion of the steam generator while simultaneously forcefully spraying water from the top portion of the generator over the bundle of heat exchanger tubes in order to remove the sludge and debris loosened by the shock waves. To conserve the water used in the flushing operation, the water that is suctioned off from the bottom portion of the steam generator is filtered and de-ionized and re-introduced through hoses at the top portion of the generator which forcefully directs water downwardly through the bundle of heat exchanger tubes and against the tubesheet. The invention greatly enhances the effectiveness of pressure pulse, water slap and water cannon cleaning methods in the secondary sides of nuclear steam generators.

System and method for vertically flushing a steam generator during a

A method for loosening and removing sludge and debris from the vessel of a heat exchanger, such as the secondary side of a nuclear steam generator, is disclosed herein. The method generally comprises the steps of providing a sufficient volume of a liquid, such as water, into the steam generator so that the lower portion which includes the tubesheet is submerged, and then generating a succession of pressure pulses within the water from one or more pressure pulse generators wherein each pressure pulse creates shock waves that exert momentary forces throughout the submerged portion of the generator of a magnitude sufficient to loosen the sludge and debris, but safely below the yield and fatigue limits of the heat exchanger tubes and other components within the generator. The pressure pulses commence as soon as a sufficient amount of water is introduced into the steam generator to submerge the tubesheet, and continue all the way through the draining of the steam generator.

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Trafford, PA, United States of America

Gregg D Auld